Reliable Raman spectroscopic authentication of ST25 rice through representative sampling of bulk grains and effective recognition of dissimilar spectral features by two-trace two-dimensional correlation analysis

Abstract

Raman spectroscopic authentication of ST25 rice through analysis of bulk grains was demonstrated. For representative spectroscopic sampling and grain packing- insensitive measurement, a packed rice sample was moved as a snake scan during spectral acquisition under a 6 mm-laser illumination, yielding a sample coverage of 70.5 cm2. When the triplicate spectra of each rice sample were collected with random grain packing, the spectral features were unchanged, demonstrating the grain packing-insensitive measurement. Next, to recognize the small spectral differences between the ST25 and non-ST25 samples, a two-trace two-dimensional correlation (2T2D-COS) analysis enabling recognition of asynchronous spectral behaviors arising from dissimilar sample compositions was employed. When the 2T2D asynchronous spectra were used for discriminant analysis using support vector machine (SVM), the accuracy was 96.6 %, while it was 88.6 % with no 2T2D-COS analysis. The achieved accuracy was attributed to both the acquisition of reproducible composition-representative spectra and sophisticated 2T2D-COS analysis.